Physicists from MIT create a new material that produces a record amount of energy under a strong magnetic field. MIT finds a way to significantly boost thermoelectricity’s potential. (Image via MIT)
We’re constantly looking for ways to make energy self-sufficient and more eco-friendly. One possible method is using the heat generated from certain objects to create energy. For instance, the heat generated from your car engine could help power your car. This is possible if improvements are made in thermoelectric materials, which spontaneously create electricity when one side of the material is heated. For years scientists have studied different materials to determine their thermoelectric potential and efficiency with which they convert heat to power. But most of these materials were found to yield efficiencies too low for any practical use. Now, MIT physicists think they have found a way to significantly increase thermoelectricity’s potential.
They used a theoretical method to model a material, which is five times more efficient and may even generate twice the amount of energy. Previously explored materials have created very little thermoelectric power because electrons are usually difficult to energize thermally. The electrons in most materials exist in specific bands or energy ranges. These bands are separated by a gap, which is a small range of energies in which electrons can’t exist. Scientists have found it extremely challenging to energize electrons enough to cross a band gap and physically migrate across a material.
MIT approached the issue by looking at the thermoelectric potential of a group of materials known as topological semimetals. Compared to other solid materials, like semiconductors and insulators, topological semimetal don’t have band gaps. Since it’s a new type of material synthesized in lab settings, scientists didn’t think it wouldn’t create much thermoelectric power. Though it did generate a good amount of energy, the charged electrons left behind “holes” or positive charge particles that pile up on the material’s cold side.
Now, they faced another challenge. How were they going to fill up these “holes?” During unrelated research, one of the team members noted how a magnetic field can affect the motion of electrons in semiconductors. They decided to apply this to the topological material and found the strong magnetic field caused the electrons and holes to move in opposite directions.
“Electrons go toward the cold side, and holes toward the hot side. They work together and, in principle, you could get a bigger and bigger voltage out of the same material just by making the magnetic field stronger.”
But it would still take an extremely strong magnetic field to generate a good amount of energy, which isn’t ideal if the material is going to be made for practical use in power plants or vehicles. They can get the desired result only if the semimetal was extremely clean, which is challenging. For now, the team is going to keep working on the project. They’re collaborating with Princeton researchers for further testing.
Have a story tip? Message me at: cabe(at)element14(dot)com
